1. Field of the Invention
The invention generally relates to the field of treatment for breathing disorders. More specifically, the present invention relates to the vent of a respiratory mask for ventilatory treatment or assistance.
The present invention also relates to an oxygen diverter valve used in systems where air or another breathable gas is mixed with oxygen. The valve may be used in conjunction with the vent. The valve has been developed primarily for use between a gas delivery apparatus for delivery of breathable gas and an oxygen port. One goal is that that when airflow is stopped the valve closes and prevents oxygen to flow upstream into the flow generator.
The valve is also suitable for use in other gas delivery systems, such as those used in assisted respiration and Non-Invasive Positive Pressure Ventilation (NIPPV).
2. Background Information
The application of Continuous Positive Airway Pressure (CPAP) via a mask is a common ameliorative treatment for sleep disordered breathing (SDB), including obstructive sleep apnea (OSA). In CPAP treatment for OSA, air or other breathable gas is supplied to the entrance of a patient's airways at a pressure elevated above atmospheric pressure, typically in the range 3-20 cm H2O as measured in the patient interface. It is also known for the level of treatment pressure to vary during a period of treatment in accordance with patient need, that form of CPAP being known as automatically adjusting CPAP treatment.
Typically, the patient interface for CPAP treatment can include a nasal mask. The nasal mask is generally defined by a mask shell that forms an inner cavity defined by its interior surface, a mask cushion and the user's face, and a gas inlet. A swivel elbow may be coupled to the gas inlet, or the gas inlet may be attached directly to a conduit that supplies the air or breathable gas. Alternatively, a nose-mouth mask, full-face mask, nasal prongs or nasal pillows may be used. One example of a nasal mask is described in U.S. patent application Ser. No. 09/570,907, which is incorporated herein by reference in its entirety.
An apparatus including a mask should be quiet and comfortable to encourage patient compliance with therapy; however, exhausting exhaled air from a vent into the atmosphere may create noise. Because CPAP treatments are normally administered while the patient is sleeping, minimization of such noise is desirable for both the comfort of the patient and any bed partner. Accordingly, a need has developed in the art to overcome the deficiencies of prior art devices that may undesirably make noise.
The inventor has discovered that a vent with fine holes or a vent covered with a finely meshed porous material similar to Gore-Tex® may be used to produce a respiratory mask having low vent noise. However, the inventor identified two potential problems encountered by the use of the vent including fine holes or the vent covered with finely meshed material. The first problem may occur if the vents of the mask become blocked or clogged with debris. The blocked vents reduce airflow through the vents, which could cause a high level of CO2 to accumulate in the mask and thereby create a safety concern to the user. The second problem may occur if the vents are manufactured with the intent of obtaining repeatable pressure flow characteristics, because it is difficult to consistently duplicate the vents of the mask at a precision required to get repeatable pressure flow characteristics.
Based upon the above, the inventor has identified a need for a vent that is quiet, comfortable, and constructed of a material that overcomes the problems of potential high CO2 levels and permits consistent pressure-flow characteristics to be achieved.